DECOMPOSITIONS OF ODD-ELECTRON AND EVEN-ELECTRON ANIONS DERIVED FROM DEOXY-POLYADENYLATES

Radical anions have been formed via electron transfer from multiply ch arged 5'-d(AAA)-3' and 5'-d(AAAA)-3' anions to CCl3+. These ions have been isolated in a quadrupole ion trap operated with helium bath gas a t a pressure of 1 mtorr and subjected to resonance excitation (i.e., c onventional ion trap collisional activation). Collisional activation o f the even-electron species of the same charge state formed directly v ia electrospray was also performed by using essentially identical cond itions. The collisional activation data can be compared directly witho ut ambiguity arising from differences in parent ion internal energies and/or dissociation time frames. Both the odd- and even-electron anion s yield extensive sequence-informative fragmentation but show signific ant differences in the extent of nucleobase loss and in the relative c ontributions from the various sequence diagnostic dissociation channel s. The results of this study indicate that radical anions derived from multiply deprotonated oligo-deoxynucleotides that survive the electro n transfer process are stable with respect to fragmentation in the ion trap environment under normal storage conditions and that the unimole cular dissociation behavior of these ions differs from the even-electr on anions of the same charge state. These findings suggest, therefore, that odd- and even-electron anions might be used to provide complemen tary sequence information in cases in which neither ion type provides the full sequence. (C) 1997 American Society for Mass Spectrometry